Ever since the early 1980s, when a pediatrician named Richard Ferber released a book that encouraged parents to let their babies cry at night, parents have been pondering the effects of letting children cry themselves to sleep. While letting your little one cry is torture to you, what exactly does it do to your child? There have been studies on the “cry it out,” or CIO, method, and you might be relieved by the results.

The Beginnings of the CIO Method

In his book, “Solve Your Child’s Sleep Problems,” Ferber came out with what many thought was a revolutionary idea: let your child cry himself to sleep. This method became so well known that many refer to it as “Ferberizing,” after the author of the book. The idea behind the method is that letting your baby cry it out at bedtime will teach him to self-sooth. According to the book, this is a skill that must be taught. If the parent constantly soothes the child to sleep, he won’t learn this important skill and will have sleep problems as he gets older.

How CIO Works

The idea of the CIO method has been adopted and adapted by many experts, such as pediatrician Marc Weissbluth and sleep expert Jodi Mindell. Most methods advise the parent to put their sleepy child to bed, reassure the child and then leave the room. Then the parent is to let the child cry for a predetermined amount of time and then the parent returns to reassure the child. The time period that the child is left to cry becomes longer each time. Eventually, days or weeks later, the parent doesn’t come back at all and the child will go to sleep without a fuss.

Those Against CIO

Though the topic is controversial, there are no recent studies on the effects of CIO that prove this type of sleep training is harmful. One popular reason why many are against CIO is a 2011 “Psychology Today” article. Darcia Narvaez, an associate professor of psychology at Notre Dame, claimed that letting a baby cry it out caused brain cells to die. To back up her claim, she cited a book called “Affective Neuroscience” by Jaak Panksepp that was published in 1998. While this book does talk about emotions, it does not specifically deal with CIO sleep training.

Regardless, you will find dozens of articles on the Internet making this claim and citing Narvaez’s article as proof. A study published in a 2004 issue of “Biological Psychiatry” did find that anxious children exhibited significantly lower nighttime cortisol levels, though this was not directly related to CIO.

Research Directly Related to CIO

The opinions of experts are all well and good, but the actual research on how the CIO method affects children is important. According to a 2012 study published in the journal “Pediatrics,” children that were raised using sleep training methods like CIO behaved no differently than children whose parents didn’t use sleep training techniques. The researchers found that there seemed to be no lasting mental or heath effects from letting the children cry.

This research seems to reveal that parents have the option of using the CIO method if it suits their parenting style.